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Commit fde86d31 authored by Eric Dumazet's avatar Eric Dumazet Committed by Linus Torvalds
Browse files

tty: add lockdep annotations 



tty_lock_pair() do the right thing to avoid deadlocks, but should
instruct LOCKDEP of this to avoid a splat.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 1d59d61f

drivers/tty/tty_mutex.c

+15 −4
Original line number Diff line number Diff line
@@ -6,11 +6,17 @@ 


/* Legacy tty mutex glue */



enum {

	TTY_MUTEX_NORMAL,

	TTY_MUTEX_NESTED,

};



/*

 * Getting the big tty mutex.

 */



void __lockfunc tty_lock(struct tty_struct *tty)

static void __lockfunc tty_lock_nested(struct tty_struct *tty,

				       unsigned int subclass)

{

	if (tty->magic != TTY_MAGIC) {

		printk(KERN_ERR "L Bad %p\n", tty);
@@ -18,7 +24,12 @@ void __lockfunc tty_lock(struct tty_struct *tty) 
		return;

	}

	tty_kref_get(tty);

	mutex_lock(&tty->legacy_mutex);

	mutex_lock_nested(&tty->legacy_mutex, subclass);

}



void __lockfunc tty_lock(struct tty_struct *tty)

{

	return tty_lock_nested(tty, TTY_MUTEX_NORMAL);

}

EXPORT_SYMBOL(tty_lock);
@@ -43,11 +54,11 @@ void __lockfunc tty_lock_pair(struct tty_struct *tty, 
{

	if (tty < tty2) {

		tty_lock(tty);

		tty_lock(tty2);

		tty_lock_nested(tty2, TTY_MUTEX_NESTED);

	} else {

		if (tty2 && tty2 != tty)

			tty_lock(tty2);

		tty_lock(tty);

		tty_lock_nested(tty, TTY_MUTEX_NESTED);

	}

}

EXPORT_SYMBOL(tty_lock_pair);